They’re predicting gloom and doom, and that Facebook may well have passed its peak in the UK. Why? Because, according to a Nielsen survey, in December the number of unique visitors the social networking site received felling from 8.9 million to 8.5 million – figures that comeafter 17 consecutive monthly increases. In the same period, MySpace UK also experienced a downturn from 5.3 million visitors to 5.1 million. Inother words, neither of them is hurting, and together they’re still responsible for more than 80% of the social networking market. But the speculation is that the fact that mainstreamfigures now have Facebook pages means it’s getting past its sell-by date, and other, hipper social networks will see a rise as the young look for something not adopted by the mainstream. Or it could simply be that the holiday season meant that people had other things to do.